如何监视计算机的CPU，内存和磁盘使用情况在Java中

import java.lang.management.ManagementFactory;
import com.sun.management.OperatingSystemMXBean;
public class OSTest {
public static void main(String[] args)
{
OperatingSystemMXBean osmb = (OperatingSystemMXBean) ManagementFactory.getOperatingSystemMXBean();
System.out.println("系统物理内存总计：" + osmb.getTotalPhysicalMemorySize() / 1024/1024 + "MB");
System.out.println("系统物理可用内存总计：" + osmb.getFreePhysicalMemorySize() / 1024/1024 + "MB"); }
File[] roots = File.listRoots();//获取磁盘分区列表
for (File file : roots) {
System.out.println(file.getPath()+"信息如下:");
System.out.println("空闲未使用 = " + file.getFreeSpace()/1024/1024/1024+"G");//空闲空间
System.out.println("已经使用 = " + file.getUsableSpace()/1024/1024/1024+"G");//可用空间
System.out.println("总容量 = " + file.getTotalSpace()/1024/1024/1024+"G");//总空间
System.out.println();
}
}

import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
private static void printUsage() {
OperatingSystemMXBean operatingSystemMXBean = ManagementFactory.getOperatingSystemMXBean();
for (Method method : operatingSystemMXBean.getClass().getDeclaredMethods()) {
method.setAccessible(true);
if (method.getName().startsWith("get")
&& Modifier.isPublic(method.getModifiers())) {
Object value;
try {
value = method.invoke(operatingSystemMXBean);
} catch (Exception e) {
value = e;
} // try
System.out.println(method.getName() + " = " + value);
} // if
} // for
}